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Mount Whyte Formation
The Mount Whyte Formation is a stratigraphic unit that is present on the western edge of the Western Canada Sedimentary Basin in the southern Canadian Rockies and the adjacent southwestern Alberta plains. It was deposited during Middle Cambrian time and consists of shale interbedded with other siliciclastic rock types and limestones. It was named for Mount Whyte in Banff National Park by Charles Doolittle Walcott, the discoverer of the Burgess shale fossils, and it includes several genera of fossil trilobites. Lithology and deposition The Mount Whyte Formation was deposited during Middle Cambrian time in shallow water at the western margin of the North American Craton. It consists mainly of shale interbedded with other siliciclastic rock types and limestone. In the Mount Whyte area it can be subdivided into three units: *Upper member: Shale interbedded with oolitic limestone. *Middle member: Shale with thin beds of sandstones and conglomerates, grading into impure lim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stratigraphic Unit
A stratigraphic unit is a volume of rock of identifiable origin and relative age range that is defined by the distinctive and dominant, easily mapped and recognizable petrographic, lithologic or paleontologic features (facies) that characterize it. Units must be ''mappable'' and ''distinct'' from one another, but the contact need not be particularly distinct. For instance, a unit may be defined by terms such as "when the sandstone component exceeds 75%". Lithostratigraphic units Sequences of sedimentary and volcanic rocks are subdivided the basis of their shared or associated lithology. Formally identified lithostratigraphic units are structured in a hierarchy of lithostratigraphic rank, higher rank units generally comprising two or more units of lower rank. Going from smaller to larger in rank, the main lithostratigraphic ranks are Bed, Member, Formation, Group and Supergroup. Formal names of lithostratigraphic units are assigned by geological surveys. Units of formation or hi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fossils Of The Burgess Shale
The fossils of the Burgess Shale, like the Burgess Shale itself, formed around 505 million years ago in the Mid Cambrian period. They were discovered in Canada in 1886, and Charles Doolittle Walcott collected over 65,000 specimens in a series of field trips up to the alpine site from 1909 to 1924. After a period of neglect from the 1930s to the early 1960s, new excavations and re-examinations of Walcott's collection continue to reveal new species, and statistical analysis suggests that additional discoveries will continue for the foreseeable future. Stephen Jay Gould's book '' Wonderful Life'' describes the history of discovery up to the early 1980s, although his analysis of the implications for evolution has been contested. The fossil beds are in a series of shale layers, averaging and totalling about in thickness. These layers were deposited against the face of a high undersea limestone cliff. All these features were later raised up above current sea level during the cr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biostratigraphy
Biostratigraphy is the branch of stratigraphy which focuses on correlating and assigning relative ages of rock Stratum, strata by using the fossil assemblages contained within them.Hine, Robert. “Biostratigraphy.” ''Oxford Reference: Dictionary of Biology'', 8th ed., Oxford University Press, 2019. The primary objective of biostratigraphy is ''correlation'', demonstrating that a particular Horizon (geology), horizon in one geological section represents the same period of time as another horizon at a different section. Fossils within these strata are useful because sediments of the same age can look completely different, due to local variations in the Sedimentary depositional environment, sedimentary environment. For example, one section might have been made up of clays and marls, while another has more chalky limestones. However, if the fossil species recorded are similar, the two sediments are likely to have been laid down around the same time. Ideally these fossils are used to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Olenellus
''Olenellus'' is an extinct genus of redlichiid trilobites, with species of average size (about long). It lived during the Botomian and Toyonian stages (''Olenellus''-zone), , in what is currently North-America, part of the palaeocontinent Laurentia. Etymology ''Olenellus fowleri'' was named in honor of Ed Fowler''Olenellus'' means small ''Olenus'', after a genus belonging to the Ptychopariida, to which the type species ''O. thompsoni'' was originally assigned. The name Olenus refers to a mythological figure who was turned to stone by the gods. The names of the species have the following derivations. * ''agellus'' comes from the Latin word for field or hamlet. * ''chiefensis'' refers to the Chief Range, which includes the Ruin Wash section, that holds the last of the Olenellina. * ''fowleri'' was named in honor of Ed Fowler, whose quarrying skills exposed the type locality of this species. * ''getzi'' is called afteNoah L. Getz on whose Lancaster estate several ''Olene ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Disconformity
An unconformity is a buried erosional or non-depositional surface separating two rock masses or strata of different ages, indicating that sediment deposition was not continuous. In general, the older layer was exposed to erosion for an interval of time before deposition of the younger layer, but the term is used to describe any break in the sedimentary geologic record. The significance of angular unconformity (see below) was shown by James Hutton, who found examples of Hutton's Unconformity at Jedburgh in 1787 and at Siccar Point in 1788. The rocks above an unconformity are younger than the rocks beneath (unless the sequence has been overturned). An unconformity represents time during which no sediments were preserved in a region or were subsequently eroded before the next deposition. The local record for that time interval is missing and geologists must use other clues to discover that part of the geologic history of that area. The interval of geologic time not represented is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Naiset Formation
The Naiset Formation is a stratigraphic unit of Middle Cambrian age. It is present on the western edge of the Western Canada Sedimentary Basin in the southern Rocky Mountains of British Columbia. It consists primarily of siliciclastic rocks, and was named for Naiset Point near Mount Assiniboine by C.E. Deiss in 1940. Thickness and lithology The Naiset Formation ranges in thickness from about 100 to 212 m (328 to 695 ft), and was deposited in a deep-water marine environment. It consists primarily of thin-bedded shale and siltstone. There are minor beds of sandstone, conglomerate, and calcareous mudstone at the base, and minor beds of oolitic and oncolitic limestone near the top. Distribution and relationship to other units The Naiset Formation is present in Rocky Mountains of southeastern British Columbia. It unconformably overlies the Gog Group. It is overlain by the Cathedral Formation, and the contact is gradational. Equivalent strata to the east of the Kicking Ho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Snake Indian Formation
The Snake Indian Formation is a stratigraphic unit of Middle Cambrian age that is present on the western edge of the Western Canada Sedimentary Basin in the northern Canadian Rockies of Alberta and British Columbia. It was named for Snake Indian River in Jasper National Park by E.W. Montjoy and J.D. Aitken in 1978. The type locality was established on Chetamon Mountain. Lithology and deposition The Snake Indian Formation was deposited in shallow marine environments along the western shoreline of the North American Craton during Middle Cambrian time. It is a thick sequence of shale and calcareous shale with interbeds of limestone and siltstone. Mudcracks in the basal shales indicate that there were periods of subaerial exposure during the early stages of deposition. Distribution and stratigraphic relationships The Snake Indian Formation is present in the northern Canadian Rockies of Alberta and British Columbia where it reaches thicknesses of up to about 610 metres (200 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Earlie Formation
The Earlie Formation is a stratigraphic unit of Middle Cambrian age in the Western Canada Sedimentary Basin that is present beneath the plains of Alberta and eastern Saskatchewan. It was named for Earlie Lake in the County of Vermilion River, Alberta, by D.C. Pugh in 1971, who described the type section based on data from an oil well drilled in that area.Glass, D.J. (editor) 1997. Lexicon of Canadian Stratigraphy, vol. 4, Western Canada including eastern British Columbia, Alberta, Saskatchewan and southern Manitoba. Canadian Society of Petroleum Geologists, Calgary, 1423 p. on CD-ROM. . Lithology The Earlie Formation consists of interbedded glauconitic siltstones and fine-grained sandstones and shales. The presence of glauconite indicates that the sediments were deposited in a marine environment. Deposition and stratigraphic relationships The Earlie Formation underlies the plains of Alberta and eastern Saskatchewan. It rests conformably on the unnamed basal sandstone unit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Outcrop
An outcrop or rocky outcrop is a visible exposure of bedrock or ancient superficial deposits on the surface of the Earth. Features Outcrops do not cover the majority of the Earth's land surface because in most places the bedrock or superficial deposits are covered by soil and vegetation and cannot be seen or examined closely. However, in places where the overlying cover is removed through erosion or tectonic uplift, the rock may be exposed, or ''crop out''. Such exposure will happen most frequently in areas where erosion is rapid and exceeds the weathering rate such as on steep hillsides, mountain ridges and tops, river banks, and tectonically active areas. In Finland, glacial erosion during the last glacial maximum (ca. 11000 BC), followed by scouring by sea waves, followed by isostatic uplift has produced many smooth coastal and littoral outcrops. Bedrock and superficial deposits may also be exposed at the Earth's surface due to human excavations such as quarrying and build ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sandstone
Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates) because they are the most resistant minerals to weathering processes at the Earth's surface. Like uncemented sand, sandstone may be any color due to impurities within the minerals, but the most common colors are tan, brown, yellow, red, grey, pink, white, and black. Since sandstone beds often form highly visible cliffs and other topographic features, certain colors of sandstone have been strongly identified with certain regions. Rock formations that are primarily composed of sandstone usually allow the percolation of water and other fluids and are porous enough to store large quantities, making them valuable aquifers and petroleum reservoirs. Quartz-bearing sandstone can be changed into quartzite through metamorphism, usually related to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oolite
Oolite or oölite (''egg stone'') is a sedimentary rock formed from ooids, spherical grains composed of concentric layers. The name derives from the Ancient Greek word for egg (ᾠόν). Strictly, oolites consist of ooids of diameter 0.25–2 millimetres; rocks composed of ooids larger than 2 mm are called pisolites. The term ''oolith'' can refer to oolite or individual ooids. Composition Ooids are most commonly composed of calcium carbonate ( calcite or aragonite), but can be composed of phosphate, clays, chert, dolomite or iron minerals, including hematite. Dolomitic and chert ooids are most likely the result of the replacement of the original texture in limestone. Oolitic hematite occurs at Red Mountain near Birmingham, Alabama, along with oolitic limestone. They are usually formed in warm, supersaturated, shallow, highly agitated marine water intertidal environments, though some are formed in inland lakes. The mechanism of formation starts with a small fragment of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Laurentia
Laurentia or the North American Craton is a large continental craton that forms the ancient geological core of North America. Many times in its past, Laurentia has been a separate continent, as it is now in the form of North America, although originally it also included the cratonic areas of Greenland and also the northwestern part of Scotland, known as the Hebridean Terrane. During other times in its past, Laurentia has been part of larger continents and supercontinents and itself consists of many smaller terranes assembled on a network of Early Proterozoic orogenic belts. Small microcontinents and oceanic islands collided with and sutured onto the ever-growing Laurentia, and together formed the stable Precambrian craton seen today. The craton is named after the Laurentian Shield, through the Laurentian Mountains, which received their name from the Saint Lawrence River, named after Lawrence of Rome. Interior platform In eastern and central Canada, much of the stable craton is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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